Field of the Invention
The invention relates to a seed crystal for producing monocrystals and to a method for producing silicon carbide monocrystals or monocrystalline silicon carbide layers.
In order to cultivate silicon carbide (SiC) monocrystals, sublimation processes are known in which a starting batch of SiC is sublimated at temperatures generally above 2000.degree. C., and an SiC monocrystal is grown on an SiC seed crystal from the sublimated SiC in the gas phase, at crystallization temperatures of generally between 1600.degree. C. and 2500.degree. C. The sublimation temperatures of the starting batch are higher than the growth temperatures at the seed crystal. A problem in sublimation cultivation of SiC is the crystal quality of the SiC monocrystals produced thereby. In particular, tubular crystal defects, known as micropipes or pinholes, impair the electronic properties of the cultivated SiC monocrystals. The problems of such crystal defects are described, for instance, in the book entitled: Physica B, Vol. 185, 1993, Elsevier science Publishers, North Holland, pp. 211-216.